This application relates to a gas turbine engine, wherein an electric motor may selectively drive a fan rotor at low power conditions of an associated aircraft.
Gas turbine engines are known and are often mounted on aircraft. In a known gas turbine engine, a fan delivers air into a core engine, and into a bypass housing as propulsion air. The air in the core housing passes to a compressor where it is compressed, and then delivered into a combustion section. The air is mixed with fuel in the combustion section and ignited. Products of this combustion pass downstream over a turbine rotor, driving the turbine rotor to rotate, and in turn drive the compressor and fan rotors.
In standard gas turbine engines, the engine is maintained operating throughout the entire flight of the associated aircraft. As known, the engine has high power conditions at take-off, and landing. the gas turbine engine would otherwise be shut down, saving fuel.
However, while the aircraft is in the air at cruise conditions, the power requirements are much lower. Thus, maintaining the engine operating throughout the entire flight results in an unnecessarily large amount of fuel consumed.
Recently it has been proposed to incorporate an electric motor to selectively drive the fan rotor, and in particular at cruise conditions. However, the proposed system has positioned the electric motor in the path of exhaust gas, and downstream of the turbine rotor. This is a very high temperature location, and results in challenges to maintaining the electric motor, and associated wires, etc., operational.